Krabbenhoft, D. P., U.S. Geological Survey, Middleton, USA, dpkrabbe@usgs.gov
Sunderland, E. ., U.S. Environmental Protection Agency, Boston, USA, Sunderland.Elsie@epamail.epa.gov
Landing, W. M., Department of Oceanography, Florida State University, Tallahassee, USA, wlanding@fsu.edu
Moreau, J. W., U.S Geological Survey, Middleton, USA, jwmoreau@usgs.gov
Hansard, S. P., Dept. of Chemistry, Colorado School of Mines, Golden, USA, shansard@mines.edu
Measures, C. ., Dept of Oceanography, University of Hawaii, Honolulu, USA, chrism@soest.hawaii.edu

DISTRIBUTIONS OF MERCURY AND METHYLMERCURY IN THE NORTH PACIFIC OCEAN

Fish harvested from the Pacific Ocean are a major contributor to population-wide mercury (Hg) exposure in the U.S. However, limited oceanic Hg data, particularly methylmercury (MeHg), has confounded our understanding of linkages between sources, methylation sites, and the effectiveness of domestic Hg emission reductions. We present results for Hg and MeHg concentrations in surface waters (<20 m) and depth profiles (~1000 m) at 15 stations between 23 and 56 degrees north. Both organic Hg and the organic Hg/total Hg ratio show distinct maxima near the oxycline, indicating water column methylation may be occurring. Atmospheric modeling results for this region suggest that highest observed surface water concentrations (<20m) coincide with enhanced atmospheric deposition near the Aleutian low. Near surface Hg concentrations are consistent with previous investigations and range between 0.6 to ~2.0 pM. However, average profile concentrations to the depth of the permanent thermocline (~1000 m) are elevated relative to 1987 and 2002 data collected at comparable latitudes. These results agree with coupled ocean-atmosphere modeling results showing Hg concentrations are likely to increase in the North Pacific over the next several decades at present global emissions levels.

Poster presentation

Presentation is given by student: No
Session #:187
Date: 03-03-2008
Time: 17:30 - 19:30